Miniature incadescent lamp having integral bulb and base

ABSTRACT

A miniature incandescent lamp having an integral bulb and base adapted for accurate frontal or rearward mounting with respect to the focal point of a reflector. The base includes axially spaced sets of radially extending locking ears and a frontal scoket having an axially projecting annular lamp support sleeve. The locking ears define first and second mounting planes having controlled positions with respect to the support sleeve. The bulb includes a filament having a controlled position with respect to an annular rim at the neck of the bulb. The rim directly engages the support sleeve to form an invariable universal connection and thereby accurately axially position the filament with respect to the mounting planes. The rim is universally adjustable about the support sleeve for accurately radially and circumferentially positioning the filament with respect to the mounting planes. A plastic cement in the socket fixedly joins the bulb to the base to maintain the radial and axial position of the filament. With this construction, the filament bears a controlled position with respect to the focal point upon seating of either of the mounting planes against the reflector.

United States Patent 1 Fuqua et al.

[111 3,749,960 [451 July 31, 1973 MINIATURE INCADESCENT LAMP HAVING INTEGRAL BULB AND BASE [75] Inventors: Lloyd T. Fuqua, Fortville; Harold E.

Todd, Anderson; both of 1nd.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

22 Filed: on. 14, 1971 21 Appl. No.: 189,434

Primary ExaminerEli Lieberman Attorney-J. L. Carpenter and P. D. Sachtjen [57] ABSTRACT A miniature incandescent lamp having an integral bulb and base adapted for accurate frontal or rearward mounting with respect to the focal point of a reflector. The base includes axially spaced sets of radially extending locking ears and a frontal scoket having an axially projecting annular lamp support sleeve. The locking ears define first and second mounting planes having controlled positions with respect to the support sleeve. The bulb includes a filament having a controlled position with respect to an annular rim at the neck of the bulb. The rim directly engages the support sleeve to form an invariable universal connection and thereby accurately axially position the filament with respect to the mounting planes. The rim is universally adjustable about the support sleeve for accurately radially and circumferentially positioning the filament with respect to the mounting planes. A plastic cement in the socket fixedly joins the bulb to the base to maintain the radial and axial position of the filament. With this construction, the filament bears a controlled position with respect to the focal point upon seating of either of the mounting planes against the reflector.

4 Claims, 11 Drawing Figures PAIENIEDJUL a I ma sum 1 or 2 INVENTORS A TTORNEY MINIATURE INCADESCENT LAMP HAVING INTEGRAL BULB AND BASE The present invention relates to incandescent electric lamps and, in particular, to miniature incandescent lamps of the type used for motor vehicle lighting applications.

Conventional motor vehicle lamp assemblies generally comprise a reflector having a lamp base mounted thereon which removably carries a miniature light bulb. The basic aim of such assemblies is to locate the filament of the bulb as accurately as possible with respect to the focal point of the reflector. In production, however, this goal is not easily achieved inasmuch as the tolerances incident to assembly tend to be cumulative and result in deviation of the filament position from the idealized location. For instance, the distance from the focal point of the reflector to the seating surface for the lamp base introduces one source of positioning error. The lamp bulb typically includes two pin connectors which are inserted into pin seats on the base to mount the bulb thereon, thereby creating another source of positioning error. A further source of error results from the tolerance between the pin seat and the mounting plane of the base. As might be expected, these tolerances result in lamp assemblies wherein the filament does not bear a precise or controlled location with respect to the focal point thereby decreasing the lighting efficiency of the assembly.

The present invention provides a lamp assembly wherein the aforementioned sources of filament positioning error are to a large extent obviated by an integral bulb and base assembly wherein the lamp filament is directly referenced to the mounting plane thereby eliminating the bulb to pin and the pin seat to mounting plane tolerances of the conventional assemblies. More particularly, the base is provided with axially spaced sets of locking ears which define front and rear mounting planes that are atrachable to and detachable from front and rear surfaces on the reflector by a simple push and twist motion. The base includes a central socket having an annular support sleeve accurately referenced in a controlled position to the mounting planes. The base additionally includes contact pins attached to the lead wires of the filament that are adapted to be connected to an electrical power source to energize the filament. The support sleeve directly engages the neck of the bulb thereby accurately axially positioning the filament at a controlled position with respect to the mounting planes. By movement of the bulb about the universal connection established between the sleeve and the neck, the filament is additionally accurately radially and circumferentially positioned at a controlled location with respect to the mounting planes. After a precise filament position is established, the socket is filled with a plastic cement which fixedly bonds the lamp to the base and protects the bulb assembly from moisture and contaminants.

With this improved construction, when the lamp is attached to the reflector, only two basic tolerances affect the position of the filament with respect to the focal point of the reflector. First, the normal focal point to seating surface tolerance on the reflector. Second, the single tolerance on the integral lamp namely, the filament to mounting plane tolerance. Inasmuch as both of these items can be closely controlled in mass production, lamp assemblies incorporating the subject design will have filaments accurately referenced to the reflector focal point and, accordingly, will provide improved output and distribution.

The above and other features of the present invention will be apparent to one skilled in the art upon reading the following detailed description, reference being made to the accompanying drawings illustrating a preferred embodiment of the present invention in which:

FIG. 1 is a partially sectioned view of a lamp assembly showing a miniature incandescent lamp made in accordance of the present invention frontally mounted on a reflector;

FIG. 1A is a fragmentary view similar to FIG. 1 showing the miniature incandescent lamp rearwardly mounted on the reflector;

FIG. 2 is a side elevational view of the miniature incandescent lamp;

FIG. 3 is a view taken along line 3-3 of FIG. 1 showing the twist-in mounting of the base on the reflector;

FIG. 4 is a view taken along line 4-4 of FIG. 1 showing the locking of the connector on the base;

FIG. 5 is a view taken along line 5-5 of FIG. 3 showing the mounting and connection between the base, the bulb, and the contact pins;

FIG. 6 is an enlarged view taken along line 6-6 of FIG. 5 showing the connection between the lead wires and the contact pins;

FIG. 7 is an enlarged fragmentary view showing the universal connection between the rim of the bulb and the seating surface of the lamp support sleeve;

FIG. 8 is an enlarged view taken along line 8-8 of FIG. 5 with the lamp and contact pins removed showing details of the socket and the support sleeve;

FIG. 9 is a schematic view showing the controlled position of the filament with respect to the support sleeve and the mounting planes of the base; and

FIG. 10 is a cross-sectional view of the light bulb.

Referring to FIG. 1, there is shown a motor vehicle lamp assembly 10 comprising a miniature incandescent lamp 12 having a major filament 14 mounted in controlled position with respect to the focal point 16 of a reflector 18. The lamp 12 is connected to a suitable power source such as the vehicle battery by a connector 19 and conventionally energized for lighting applications such as tail, stop, or directional lamps. However, the present invention is applicable in all lighting installations and, in particular, lamp assemblies requiring a filament which is accurately located in a controlled position with respect to a reflector.

The reflector 18 is conventional in construction, for instance a zinc diecasting, and has a parabolic inner reflective surface 20 having an axis 21 and the aforementioned focal point 16. The reflector 18 includes a central circular mounting boss 22 having a rear seating surface 24 and a front seating surface 26. The mounting boss 22 includes a center aperture hereinafter described for detachably receiving the lamp 12. For fronta] mounting wherein the lamp is inserted through the aperture from the front, the lamp 12 seats against the rear seating surface 24 of the mounting boss 22 as shown in FIG. 1. For rearward mounting wherein the lamp 12 is inserted through the aperture from the rear, the lamp 12 seats against the front seating surface 26 of the boss 22 as shown in FIG. 1A.

Referring to FIGS. 1 through 3, the lamp 12 generally comprises a twist-in base 30 and a light bulb 32. The base 30 carries a sealing and biasing gasket 34 at its front section 35 and three circumferentially spaced axially extending contact pins 36 at its rear section 37. The front section 35 of the base 30 includes flanges comprising two sets of three axially spaced, radially outwardly projecting locking ears 40 and 42, respectively. The locking cars 40 and 42 are equally circumferentially spaced about the periphery of the front section 35. However, one of the ears in each set is slightly smaller in size than the others to permit indexing of the lamp 12 on the reflector 18. The rear set of locking ears 40 have front seating surfaces defining a rearward mounting plane 44. The front set of locking ears 42 have rear seating surfaces defining a front mounting plane 46.

As shown in FIG. 3, the seating boss 22 of the reflector 18 includes a center opening 50 slightly larger in diameter than the front section 35 and the bulb 32 for permitting passage therethrough of the lamp 12 for either frontal or rearward mounting. The seating boss 22 includes arcuate notches 52 formed adjacent the opening 50. The notches 52 are circumferentially spaced and shaped congruently with the locking ears 40, 42. The locking ears 40 and 42 include lead surfaces 56 and 58, respectively, for facilitating camming of the lamp 12 into position on the reflector 18 upon applying a twisting movement to the lamp 12. A pin 60 on the seating boss 22 cooperates with the smallest locking ear to circumferentially index the lamp 12.

The gasket 34 is retained in an outwardly opening annular groove 62 formed in the front section 35 of the base 30. The gasket 34 is formed of a suitable elastomeric material and has a generally T-shaped cross section including an annular base received in groove 62.

In assembly, for frontal mounting, the rearward rim of 5 the gasket 34 compressively engages the seating boss 22 to bias the rearward locking ears 40 against the rear seating surface 24. For rearward mounting, the front rim of the gasket 34 engages the seating boss 22 to bias the frontal locking ears 42 against the seating front surface 26.

Referring to FIGS. 5 through 8, the front section of the base 30 is provided with a central forwardly opening socket 70. An annular lamp support sleeve 72 projects axially forwardly from the base of the socket 70. The sleeve 72 and the base and sidewall of the socket 70 define a lower annular channel 74. A central cavity 76 is formed in the sleeve 72. The front portion of the support sleeve 72 includes alternate lands 78 and grooves 80. The lands 78 have spherical or conical seating surfaces having a controlled position with respect to the aforementioned mounting planes 44 and 46. Three axially extending apertures 82 adapted to frictionally receive the contact pins 36 are formed in the rear section 37 of the base 30 and register with the channel 74.

Referring to FIG. 10, the bulb 32 is conventional in construction and generally comprises an outer shell 90 and a central stem 92, the inner surfaces of which define a lamp envelope 93. The shell 90 and the stem 92 are fusion joined at a neck 94 that terminates at an annular rim 96. Pairs of lead wires 98 and 100 extend through the stem 92 for respectively supporting the aforementioned major filament 14 and a minor filament 102 in a conventional manner. The lead wires 98, 100 respectively include free ends 104, 106 that extend rearwardly through the stem 92. The lamp envelope 93 is filled with an inert gas through an exhaust tube 108 which is tipped off to seal the envelope 93.

Referring to FIGS. 5 and 6, each contact pin 36 includes a leg portion 110 extending through the aperture 82, a head portion 112 projecting into the channel 74, and an intermediate shoulder portion 114 which engages the base of the channel 74. In assemblying the bulb 32 to the base 30, the head portions 112 are clinched at three places to capture and fixedly secure the free ends 104, 106. After this connection, each contact pin 36 is inserted through the aperture 82 until the shoulder 114 engages the base of the channel 74 to thereby axially locate the pins 36. This will preliminarily position the rim 96 adjacent the seating surfaces of the lands 78.

As shown in FIGS. 5 and 7, after preliminary positioning, the rim 96 is seated against the lands 78 with the free ends 104, 106 extending through the grooves 80. This establsihes an invariable universal connection between the support sleeve 72 and the bulb 32. The seating of the rim 96 against the lands 78 will also axially position the filament 14 at a controlled location with respect to the mounting planes 44 and 46. By universally positioning the bulb 32 with respect to the lands 78, the filament 14 will be radially and circumferentially positioned at a controlled position with respect to the mounting planes 44 and 46.

When the desired position of the filament 14 with respect to the mounting planes 44, 46 has been achieved, the bulb 32 is fixedly attached to the base 30 by means of a plastic cement received in the socket 70. This may be achieved in a number of ways. For instance, the plastic cement 120 may be depositioned in liquid form prior to alignment or injected into the socket 70 after alignment. However, any method may be used which will fixedly maintain the aligned relationship. The cement 120 additionally serves to seal the lead wires from outside contaminants and moisture and the captured air space in the cavity 76 permits breathing of the lead wires which prolongs the life of the lamp 12.

As shown in FIGS. 1 and 4, the connector 19 is formed of a nonconductive plastic material and includes appropriate metal sockets for frictionally gripping the contact pins 36. The connector 19 includes slotted flexible arms 115, 116 which snap over tabs 117, 118 on the rear sections 37 to lock the connector 19 onto the base 30. The connector 19 is conveniently connected to a power source such as the vehicle battery for selectively energizing the lamp.

The advantages accruing from the above-described construction are more easily understood by reference to FIG. 9. As previously mentioned, the filament 14 will have a controlled position A with respect to the rim 96 and seating surfaces of the lands 78. This position can be maintained within 10.015 in. Additionally, the seating surfaces of the lands 78 will have controlled positions B and C with respect to the mounting planes 44 and 46 which will typically have tolerances of about $0010 in. Therefore, it will be assured that the location of the filament 14 with respect to the seating planes 44 and 46 will have a positional accuracy of around i0.025 in. The normal tolerance between the seating surface of the reflector and the focal point '16 will be around $0.010. Accordingly, in assembly, the lamp 10 and the filament 14 will be aligned with respect to the focal point 16 within 20.035 in. This is in contrast to conventional units having a separate base and bulb construction wherein the filament to pin tolerance is about i0.040, the pin seat to mounting plane tolerance is about 10.020, giving total assembly tolerance of around 10.070 in. Quite obviously, this 50 percent reduction in filament placement error will result in substantially increased lighting efficiency.

Although only one formof this invention has been shownand described, other forms will be readily apparent to those skilled in the art. Therefore, it is not intended to limit the scope of this invention by the em-' bodiment selected for the purpose of this disclosure but only by the claims which follow.

We claim: I

l. A lamp assembly comprising: a bulb member; a filament means carried by said bulb member; an annular surface on said bulb member having a controlled position with respect to said filament means; a base member; seating surface means formed on said base member and engaging said annular surface on said bulb member for axially positioning said filament means and for establishing a universal connection for radially positioning said filament means thereabout thereby directly referencing said filament means to said base member; means on said base member for mounting the lamp as sembly on a mounting surface, said means having a controlled position with respect to said seating surface means thereby additionally directly referencing the position of said filament means to said means on said base member and thereby said mounting surface; lead means for connecting the filament means to a source of electrical power; and means securing the bulb member to the base member thereby fixedly positioning the assembly.

2. A miniature incandescent lamp comprising: a light bulb having an outer shell defining a lamp envelope; an annular rim on said light bulb; a filament supported on said bulb interior of said lamp envelope, said filament having a controlled position with respect to said rim; a base having a center cylindrical socket for receiving said rim of said bulb; an annular sleeve projecting from said socket, said sleeve having a bearing surface engaging the rim for axially positioning said filament and establishing a universal connection for radially positioning the filament thereby providing a direct reference on said base for the actual position of the filament; flange means projecting on said base for engaging a mounting surface for mounting the assembly, said flange means defining a mounting plane having a controlled position with respect to the rim whereby said controlled positions permit direct referencing of the filament to said mounting surface; lead means for connecting the filament to a source of electrical power; and means in the. socket integrally structurally securing the bulb to the base and sealing said lead means.

3. An integral bulb and base lamp assembly comprising: a light bulb having an outer shall and a reentrant stem joined at an annular rim, said shell and said stem defining a lamp envelope; a filament supported on the stem interior of said envelope having a controlled position with respect to said rim; lead wires connected to the filament and extending outwardly through said stem; a base having a center socket for receiving said rim of said bulb; an annular sleeve projecting from said socket, said sleeve having an annular bearing surface includingalternately circumferentially spaced lands and grooves, the engagement between said lands and said rim establishing an invariable universal connection for radially and axially positioning the filament thereby providing a direct reference at said socket for the actual position of the filament; a radially outwardly projecting flange on said base for engaging a reference surface for mounting the assembly, said flange defining a mounting plane having a predetermined position with respect to said rim whereby said predetermined position permits direct referencing of the filament position to said mounting plane thereby reducing intermediate positioning tolerances between the bulb and the base; contact means attached to said lead wires for connecting said filament to a source of electrical power; and a plastic cement in the socket fixedly securing the bulb to the base and sealing said lead wires thereby fixedly positioning and sealing the assembly.

4. In a lamp assembly having a reflector including a center opening having circumferentially spaced notches formed adjacent thereto, a miniature incandescent lamp for mounting in controlled position to the focal point of the reflector comprising: a plastic base having a substantially cylindrical socket formed therein, said base including a forwardly projecting annular support sleeve in said socket; an annular channel formed at the base of the socket; a plurality of circumferentially alternating grooves and substantially spherical lands formed on said support sleeve; axially spaced sets of outwardly projecting ears on said base, said cars' and said base being either forwardly or rearwardly insertable through said notches and said center opening on the reflector, said base being rotatable within the opening to cause said ears to engage the remote surface of said reflector for front or rear mounting of the assembly thereon, said ears defining mounting planes having controlled positions with respect to the lands; a light bulb having an outer shell and a reentrant stem fusion joined at a circular neck terminating with a rearward annular rim wherein said stern and said neck define a sealed lamp envelope, said neck being received within said socket with said lands engaging said rim and establishing an invariable universal connection for axially, radially and circumferentially positioning said bulb;'a filament supported on said stern interior of the envelope, said filament having a controlled position with respect to said annular rim thereby directly referencing the filament to said lands and said mounting planes; lead wires connected to the filament and extending through the grooves to said channel; contact pins extending from said channel rearwardly through said base, said pins being connected to said lead wires for connecting the filament to a source of electrical power; and a plastic cement in said socket and said channel integrally structurally securing said bulb to said base and sealing said lead means.

I k I P0405) UNITED STATES PATENT OFFICE CER'MMCTE l Efilld Patent 174%960 Dated l 31 1973 Inventor(s) Lloyd '1, Fuqua, Harold Eo Todd It is certified that error appears in the above ident ified patent and that said Letters Patent are hereby corrected as shown below:

Title page, title, 'INCADESCENT" should read INCANDESCENT -fl,

Abstract, line 5, "scoket" should read socket Column 1, title, Ill Am should read INCANDESCENT g; line 39, atrachable should read attachable Column 4, line l9, esdzelalsllues should read establishes '--=-o Column 5, line 56, shall should read shell Column 6, line d, "ihcludingalternately" should read including alternately n Signed and sealed this 29th day of'0ctober 1974.,

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents 

1. A lamp assembly comprising: a bulb member; a filament means carried by said bulb member; an annular surface on said bulb member having a controlled position with respect to said filament means; a base member; seating surface means formed on said base member and engaging said annular surface on said bulb member for axially positioning said filament means and for establishing a universal connection for radially positioning said filament means thereabout thereby directly referencing said filament means to said base member; means on said base member for mounting the lamp assembly on a mounting surface, said means having a controlled position with respect to said seating surface means thereby additionally directly referencing the position of said filament means to said means on said base member and thereby said mounting surface; lead means for connecting the filament means to a source of electrical power; and means securing the bulb member to the base member thereby fixedly positioning the assembly.
 2. A miniature incandescent lamp comprising: a light bulb having an outer shell defining a lamp envelope; an annular rim on said light bulb; a filament supported on said bulb interior of said lamp envelope, said filament having a controlled position with respect to said rim; a base having a center cylindrical socket for receiving said rim of said bulb; an annular sleeve projecting from said socket, said sleeve having a bearing surface engaging the rim for axially positioning said filament and establishing a universal connection for radially positioning the filament thereby providing a direct reference on said base for the actual position of the filament; flange means projecting on said base for engaging a mounting surface for mounting the assembly, said flange means defining a mounting plane having a controlled position with respect to the rim whereby said controlled positions permit direct referencing of the filament to said mounting surface; lead means for connecting the filament to a source of electrical power; and means in the socket integrally structurally securing the bulb to the base and sealing said lead means.
 3. An integral bulb and base lamp assembly comprising: a light bulb having an outer shall and a reentrant stem joined at an annular rim, said shell and said stem defining a lamp envelope; a filament supported on the stem interior of said envelope having a controlled position with respect to said rim; lead wires connected to the filament and extending outwardly through said stem; a base having a center socket for receiving said rim of said bulb; an annular sleeve projecting from said socket, said sleeve having an annular bearing surface includingalternately circumferentially spaced lands and grooves, the engagement between said lands and said rim establishing an invariable universal connection for radially and axially positioning the filament thereby providing a direct reference at said socket for the actual position of the filament; a radially outwardly projecting flange on said base for engaging a reference surface for mounting the assembly, said flange defining a mounting plane having a predetermined position with respect to said rim whereby said predetermined position permits direct referencing of the filament position to said mounting plane thereby reducing intermediate positioning tolerances between the bulb and the base; contact means attached to said lead wires for connecting said filament to a source of electrical power; and a plastic cement in the socket fixedly securing the bulb to the base and sealing said lead wires thereby fixedly positioning and sealing the assembly.
 4. In a lamp assembly having a reflector including a center opening having circumferentially spaced noTches formed adjacent thereto, a miniature incandescent lamp for mounting in controlled position to the focal point of the reflector comprising: a plastic base having a substantially cylindrical socket formed therein, said base including a forwardly projecting annular support sleeve in said socket; an annular channel formed at the base of the socket; a plurality of circumferentially alternating grooves and substantially spherical lands formed on said support sleeve; axially spaced sets of outwardly projecting ears on said base, said ears and said base being either forwardly or rearwardly insertable through said notches and said center opening on the reflector, said base being rotatable within the opening to cause said ears to engage the remote surface of said reflector for front or rear mounting of the assembly thereon, said ears defining mounting planes having controlled positions with respect to the lands; a light bulb having an outer shell and a reentrant stem fusion joined at a circular neck terminating with a rearward annular rim wherein said stem and said neck define a sealed lamp envelope, said neck being received within said socket with said lands engaging said rim and establishing an invariable universal connection for axially, radially and circumferentially positioning said bulb; a filament supported on said stem interior of the envelope, said filament having a controlled position with respect to said annular rim thereby directly referencing the filament to said lands and said mounting planes; lead wires connected to the filament and extending through the grooves to said channel; contact pins extending from said channel rearwardly through said base, said pins being connected to said lead wires for connecting the filament to a source of electrical power; and a plastic cement in said socket and said channel integrally structurally securing said bulb to said base and sealing said lead means. 